Trunk Angle / Lean
trunk line (hip → shoulder) vs vertical (squat) or lateral lean vs vertical (single-leg).
Why this matters
Forward trunk lean in a squat is a window into ankle/hip restriction; lateral trunk lean in a single-leg task exposes hip-abductor (gluteus medius) control.
What good looks like
- Squat: trunk roughly parallel to the shin, not collapsing forward.
- Single-leg: torso stays stacked over the pelvis with minimal sideways lean.
Common faults
- Excessive forward lean → check ankle dorsiflexion.
- Lateral lean toward the stance leg → hip-abductor weakness (often with pelvic drop + knee valgus).
Related
source · sports/performance/learn/trunk_lean.md